The spectral index map also shows the same general spectral properties of the source that have been seen either at much lower angular resolution or at higher radio frequencies (e.g. [1]}, [2]}), that is, a steepening of the spectral index from around \(\alpha = -0.65\pm 0.02\)  in the lobe and counter-lobe regions to around \(\alpha = -0.95\pm 0.14\)  at the location of the core. The plume region, which extends south of the core, has the steepest spectral index of any part of the source, with \(\alpha = -1.25\pm 0.07\) . This variation in the spectral properties of the source agrees with what we would expect given previously reported spectral ageing models (e.g. [3]}). There is also evidence for spectral structure within the lobes, particularly within the counter-lobe. However, we defer any detailed discussion of these features to a follow-up paper.
